It is well known in the prior art to manufacture tire components from elastomeric sheets of rubber which are then cut to length with the ends joined together by a lap or butt splice onto a cylindrically shaped building drum. Since the tire components are assembled flat onto a cylindrical tire building drum and then expanded into a toroidal shape, each component has to be placed in tension or compression prior to being molded. This stretching of the various parts causes slippage between the various rubber parts as the components heat up during vulcanization. Attempts to minimize the slippage of the various parts have been attempted. Another disadvantage is that the tire has components which are spliced, wherein the splices contribute to tire nonuniformity.
Tire manufacturers have been increasingly focusing their efforts on eliminating tire nonuniformities. More recently, tire manufacturers are making tire components from a continuous strip of unvulcanized rubber. A thin, narrow strip of unvulcanized rubber is circumferentially wound multiple times onto a rotating drum or toroid shaped core, wherein the strips are successively layered or stacked in order to form the desired shape of the tire component. See for example, U.S. Pat. Nos. 6,372,070 and 4,963,207. The strip of rubber is typically extruded directly onto a tire building drum or toroidal-shaped core using an extruding device. Alternatively the strips may be formed from calendering and then conveyed to the tire drum or core.
This strip lamination method of forming tire components has the advantage of eliminating splices because the annular tire component is typically formed of one continuous strip. Strip lamination has the further advantage of allowing flexibility in manufacturing, since the tire component profile may be changed from tire to tire.
It is known to extrude the rubber through a nozzle or shaping die and to apply the strip of rubber using a roller or stitcher to a tire building drum. However, these systems typically have the disadvantage of causing high pressure and high temperature of the rubber in the system due to the small exit area opening. If the residence time of the rubber is too slow through the system, the rubber may be scorched if the temperature is too high. Thus it is desired to have an improved system which will lower the system temperature and pressure while forming the desired shape of the rubber strip.